# CVE-2026-46033: crypto: authencesn - reject short ahash digests during instance creation

> A flaw in the Linux kernel's authencesn crypto module allows out-of-bounds access via short digests, potentially leading to code execution or denial of service.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 May 2026
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-88428, BELL-CVE-2026-46033, DEBIAN-CVE-2026-46033, GHSA-f7w2-rj2f-73q3, ROOT-OS-DEBIAN-11-CVE-2026-46033, ROOT-OS-DEBIAN-12-CVE-2026-46033, ROOT-OS-UBUNTU-2204-CVE-2026-46033, ROOT-OS-UBUNTU-2404-CVE-2026-46033, UBUNTU-CVE-2026-46033

## What is CVE-2026-46033?

CVE-2026-46033 is a high-severity memory corruption vulnerability in Linux kernel, published on 27 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

crypto: authencesn - reject short ahash digests during instance creation

authencesn requires either a zero authsize or an authsize of at least
4 bytes because the ESN encrypt/decrypt paths always move 4 bytes of
high-order sequence number data at the end of the authenticated data.

While crypto_authenc_esn_setauthsize() already rejects explicit
non-zero authsizes in the range 1..3, crypto_authenc_esn_create()
still copied auth->digestsize into inst->alg.maxauthsize without
validating it.  The AEAD core then initialized the tfm's default
authsize from that value.

As a result, selecting an ahash with digest size 1..3, such as
cbcmac(cipher_null), exposed authencesn instances whose default
authsize was invalid even though setauthsize() would have rejected the
same value.  AF_ALG could then trigger the ESN tail handling with a
too-short tag and hit an out-of-bounds access.

Reject authencesn instances whose ahash digest size is in the invalid
non-zero range 1..3 so that no tfm can inherit an unsupported default
authsize.

Weakness: CWE-1284 (Improper Validation of Specified Quantity in Input), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-46033?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46033?

Apply the vendor's patch.

## Is CVE-2026-46033 being exploited?

There is no known exploitation of CVE-2026-46033 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46033 and fix it if it is affected.

What it is: CVE-2026-46033 is a high-severity memory corruption vulnerability in Linux kernel, published on 27 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-46033 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-46033/ (Markdown: https://insights.sbomify.com/CVE-2026-46033/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46033
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46033
- OSV: https://osv.dev/vulnerability/CVE-2026-46033

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46033/
Summaries are generated and may contain mistakes; the official description above is the record.